Monday, November 13, 2006 - 3:10 PM

Agricultural Management of Enhanced Efficiency Fertilizers: Great Plains.

Walter Gordon, Kansas State Univ, 1300 60 Rd, Courtland, KS 66939

No-tillage corn production systems are being used by an increasing number of producers in the central Great Plains. The large amounts of residue left on the soil surface can make nitrogen (N) and phosphorus (P) management more difficult. Surface applications of urea-containing fertilizers are subject to volatilization losses. Immobilization and leaching losses also can be problems.  Urea-containing N products coated with a urease inhibitor have been available for some time and slow release, polymer coated urea products are becoming available for agricultural use.  To establish if polymer-coated, slow release urea could provide an improved N-management tool, experiments were conducted at the North Central Kansas Experiment Fields, on a Crete silt loam soil. Corn was grown for three years with three rates of N applied as urea, ammonium nitrate,  polymer coated  urea, and urea coated with a urease inhibitor. Both the polymer coated urea and the urease inhibitor coated urea proved to be more effective than conventional urea fertilizer. Phosphorus can readily react with soil cations such as calcium, magnesium, iron and aluminum to produce various phosphate compounds of limited water solubility. Crop recovery of applied P fertilizer can be quite poor during the season of application. Recently a patented dicarboxylic co-polymer compound has been developed   that is reported to sequester antagonistic cations out of the soil solution, thus keeping P fertilizer in a more plant-available form.  In a three year study with corn, polymer treated mono-ammonium phosphate (MAP) was compared to conventional MAP at three rates of application.  The use of the polymer coated MAP consistently increased plant P concentration and yield when compared to conventional MAP. Resent innovations in technology have provided producers with new, more efficient ways to manage crop fertilizer application.